Early adenovirus-based gene therapy usually employs replication-incompetent adenoviruses carrying a therapeutic gene with deleted E1 gene essential for adenovirus replication. However, these recombinant adenoviruses induce anti-tumor activity only in infected cells and a very small number of surrounding cells, exhibiting serious problems in clinical applications (Vile R G, Russell S J, Lemoine N R., Gene Ther, 2000, 7(1):2-8). To overcome such problems, the oncolytic adenovirus, ONYX-015(d11520) selectively replicating in tumor cells was first developed by McCormick research group (Bischoff J R, et al., Science, 1996, 274(5286):373-376; Heise C, et al., Nat Med, 1997, 3(6):639-645). The E1B kDa gene-deleted adenovirus selectively replicates in tumor cells lacking functional p53. When the recombinant adenovirus infects normal cells, its proliferation is inhibited to result in the failure of oncolysis because p53 inactivation is not induced, whereas it actively proliferates in tumor cells with inactivated p53 and eventually leads to selective death of tumor cells (Chang, F., et al., J Clin Oncol 13:1009-22(1995)).
According to recent reports on Phase-II/III clinical trials for brain cancer, a tumor-specific oncolytic adenovirus exhibits considerable therapeutic efficacy (Kirn, D., et al., Nat Med 4:1341-2(1998); Nemunaitis, J. et al., Cancer Res 60:6359-66(2000); and Ganly, I. et al., Clin Cancer Res 6:798-806(2000)). Although the administration of the recombinant adenovirus induces the partial suppression of tumor growth, the complete eradiation of tumor does not been found and regrowth of tumor rapidly occurs after the lapse of a period of time. Theses results are probably because the recombinant adenovirus topically injected into tumor are partially spread within a limited surrounding portion to elicit a restricted anti-tumor activity such that tumor cells not infected with viruses rapidly grow. According to a recent research report, the recombinant adenoviruses administered into human tumor in nude mice persistently replicate as late as 100 days after initial viral injection and do not ensure the complete eradication of tumor, while viable viruses may be obtained from tumor tissue. According to subsequent research reports, it has been clarified that those low anti-tumor effects are because the connective tissue and extracellular matrix (ECM) present in cell play a prominent role in inhibiting viral spread of recombinant adenoviruses. Moreover, when adenoviruses are injected into tumor, in early stage, they are rapidly eradicated from blood stream by innate immune reaction; however, on about 48 weeks after viral injection, adenoviruses presumed to be replicated in tumor and released to the blood stream could be observed to appear again in the blood stream. Taking those successive results into consideration, it could be recognized that the physical barriers such as connective tissue and extracellular matrix (ECM) between tumor cells is likely to inhibit viral spread and then to highly decrease the anti-tumor effect of adenoviruses, although tumor-specific oncolytic adenoviruses administered are actively replicated in tumor cells.
Consequently, it could be appreciated that the ideal tumor-specific oncolytic adenovirus has the ability to induce greater oncolytic activity and spread throughout tumor tissue as well for infecting surrounding tumor cells.
Recently, several investigations have been reported to conquer low transduction efficiency of viral gene carriers resulting from their limited spreading potential within tissues. N. Kuriyama et al. reported that either collagenase/dispase or trypsin to digest collagen and other components of extracellular matrix enhanced viral infection, indicating that protease pretreatment may be a useful strategy for enhancing virus-mediated gene transduction (Kuriyama N, et al., Hum Gene Ther, 2000, 11(16):2219-2230). Moreover, L. Maillard et al. attempted to elevate the efficiency of adenovirus-mediated gene transfer by about two-fold by treating rabbit iliac arteries with elastinase, an enzyme which dissociates elastin, which is an essential component of arteries (Maillard, L., et al., Gene Ther, 1998, 5(8):1023-1030). There was a report that hyaluronidase, an enzyme which dissociates extracellular matrix, could enhance the gene transduction efficiency of adeno-associated viruses in the rat muscle by about 2-3 folds (Favre D, et al., Gene Ther, 2000, 7(16):1417-1420). Through the results of these successive investigations, it would be understood that the decrease in extracellular components by either inhibiting the synthesis of extracellular components or facilitating the dissociation of extracellular components may increase the spreading of viruses in tissues, thereby improving the efficiency of gene transduction by viruses. Moreover, it would be recognized that obstructing extracellular matrix assembly may prevent and treat fibrotic diseases such as keloid caused by abnormal proliferation of skin connective tissues.
Throughout this application, several patents and publications are referenced and citations are provided in parentheses. The disclosure of these patents and publications is incorporated into this application in order to more fully describe this invention and the state of the art to which this invention pertains.